A 34-year-old O'Fallon man has been sentenced to life in prison for the death of his girlfriend's 4-month-old infant.

Devon Coleman was sentenced Monday for killing Dexter Gabel in December 2017 at a home in O'Fallon. He was found guilty in May of child abuse resulting in death.

Court documents indicate Coleman told police he put the baby in a crib for a nap when he would not stop crying. He said the infant had stopped breathing when he returned.

A medical examiner determined Dexter's injuries were consistent with asphyxiation by strangling or smothering, and he also had bruises on his head and face.

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